As a valve opening/closing timing control apparatus configured as described above, JP 2004-257313A (Reference 1) discloses a technique in which a driven side rotational body is included in a driving side rotational body, and a lock member configured to be engaged to or disengaged from a lock recess formed in the driven side rotational body is supported to freely protrude from or retreat into the driving side rotational body in a radial direction, and biased in a protrusion direction by a spring.
In Reference 1, a pair of lock members and a pair of lock recesses respectively corresponding to the respective lock members are formed, and a stepped portion is formed in at least one of the lock recesses. The reason why the stepped portion is formed is that when shifting to a locked state, one of the lock members, which corresponds to the stepped portion, is engaged with the stepped portion to reduce a region in which a relative rotational phase fluctuates, and to facilitate the fitting of the other lock member into the lock recess.
Providing a pair of lock members as described in Reference 1 is to facilitate the shifting to the locked state as compared with providing a single lock member.
However, when the lock members are supported to freely protrude from or retreat into the driving side rotational body, and the lock recesses to be engaged with the lock members are formed in the driven side rotational body as described in Reference 1, a large force may act on the lock members in the shear direction due to a rotation force transmitted from the driving side rotational body to the driven side rotational body, or a cam fluctuating torque during the operation of the engine. Thus, in some cases, a rapid lock release may not be carried out even though hydraulic oil is supplied to the lock recesses.
In order to solve the problem, the lock release has been carried out in a state where the action of the shear force is suppressed by supplying the hydraulic oil to an advanced angle chamber or a retarded angle chamber. That is, in order to suppress the shear force acting on one lock member, the lock of the one lock member is released by supplying the hydraulic oil to one of the advanced angle chamber and the retarded angle chamber. Then, in order to suppress the shear force acting on the other lock member, the lock of the other lock member is released by supplying the hydraulic oil to the remaining one of the advanced angle chamber and the retarded angle chamber.
However, in such a control mode, time is required not only for the control of the valve, but also until the hydraulic pressure acts in a direction that changes the relative rotational phase. As a result, time is required to release the locked state.